org.apache.taglibs.standard.tag.common.core.CatchTag Maven / Gradle / Ivy
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package org.apache.taglibs.standard.tag.common.core;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.tagext.TryCatchFinally;
/**
* Tag handler for <catch> in JSTL 1.0.
*
* <catch> simply catches any Throwables that occur in its body
* and optionally exposes them.
*
* @author Shawn Bayern
*/
public class CatchTag extends TagSupport implements TryCatchFinally {
/*
* If all tags that I proposed were this simple, people might
* think I was just trying to avoid work. :-)
*/
//*********************************************************************
// Constructor and lifecycle management
// initialize inherited and local state
public CatchTag() {
super();
init();
}
// Releases any resources we may have (or inherit)
public void release() {
super.release();
init();
}
private void init() {
var = null;
}
//*********************************************************************
// Private state
private String var; // tag attribute
private boolean caught; // internal status
//*********************************************************************
// Tag logic
public int doStartTag() {
caught = false;
return EVAL_BODY_INCLUDE;
}
public void doCatch(Throwable t) {
if (var != null)
pageContext.setAttribute(var, t, PageContext.PAGE_SCOPE);
caught = true;
}
public void doFinally() {
if (var != null && !caught)
pageContext.removeAttribute(var, PageContext.PAGE_SCOPE);
}
//*********************************************************************
// Attribute accessors
public void setVar(String var) {
this.var = var;
}
}